Various benzimidazole compounds are known for their use as anthelmintic agents, such as disclosed in U.S. Pat. Nos. 3,929,821, 3,929,822, 3,929,823, 3,929,824, 3,935,209, 3,965,113, 4,002,640 and 4,005,202 all to Beard et al. and assigned to Syntex; 3,574,845 and 3,682,952 to Actor, 3,578,676 and 3,694,455 to Dunn, 3,915,986 and 3,969,526 to Gyurik, all assigned to Smith Kline; 3,738,993 to Haugwitz et al.
U.S. Pat. No. 4,002,640 discloses benzimidazole compounds which have the structure ##STR2## wherein R is lower alkyl having 1 to 4 carbon atoms, R.sup.1 may be --SR.sup.5, and R.sup.5 may be lower alkenyl, wherein the double bond is not on the .alpha.-carbon. Specific compounds disclosed include 5(6)-(prop-2-en-1-ylthio)-2-carbomethoxyaminobenzimidazole, and 5(6)-(prop-2-en-1-ylsulfinyl)-2-carbomethoxyaminobenzimidazole. These compounds as well as the benzimidazoles disclosed in all of the aforementioned patents are said to be active perorally in the treatment of helminthiasis.
U.S. Pat. Nos. 3,954,791 to Loewe et al and 3,928,375 to Duwel et al, both assigned to Hoechst disclose 2-carbalkoxy-amino-benzimidazole-5(6)-phenyl ethers (and thioethers) which are said to be active perorally as well as subcutaneously.